Post-processing-induced improvements in the bending behavior of SLM-produced Ti6Al4V alloy

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Önder S., Saklakoğlu N., Sever A., Başar G.

INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY, vol.143, no.3-4, pp.1679-1693, 2026 (SCI-Expanded, Scopus)

  • Publication Type: Article / Article
  • Volume: 143 Issue: 3-4
  • Publication Date: 2026
  • Doi Number: 10.1007/s00170-026-17644-2
  • Journal Name: INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, IBZ Online, Compendex, INSPEC, DIALNET
  • Page Numbers: pp.1679-1693
  • Keywords: Selective laser melting, Ti6Al4V, Multiscale characterization, Process-structure-property relationship, Post-processing, Three-point bending
  • Open Archive Collection: AVESIS Open Access Collection
  • Dokuz Eylül University Affiliated: Yes

Abstract

This study presents a multiscale evaluation of the effects of various post-processing strategies, including machining, shot peening (SP), and heat treatment, on the static bending behavior of Ti6Al4V alloy produced by selective laser melting (SLM). Five specimen groups were prepared: as-built, milled, milled followed by traditional SP, milled followed by dual SP, and annealed before milling. To establish a detailed structure-property relationship, the study integrates surface roughness measurements, microstructural and fracture surface characterizations with three-point bending tests. Milling significantly improved surface quality, reducing the average surface roughness (R-a) from 17.05 mu m in the as-built specimens to 0.43 mu m in the only machined ones. This significant reduction contributed to higher bending strength and bending strain compared with the as-built specimens. While conventional SP slightly increased the surface roughness amplitude (R-a, R-z, and R-c), the secondary SP with smaller-diameter shots reduced roughness amplitude again and resulted in a more homogeneous surface topography. Machining alone improved bending strength by 23%, whereas dual SP yielded the highest strength with a 34% increase relative to the as-built specimens, due to induced compressive residual stresses, martensitic alpha ' lath refinement, reduced surface roughness, and higher dislocation density. Heat treatment transformed the martensitic alpha ' phase in prior beta grains into an alpha + beta structure, and the annealed and machined specimens exhibited a 264% increase in bending strain relative to the as-built specimens and 184% compared to the only machined specimens, with ductility enhancement primarily governed by the alpha + beta transformation and supported by reduced surface roughness.